Electrophotographic photosensitive members including a support, an undercoat layer formed on the support, and a photosensitive layer formed on the undercoat layer and containing an organic photoconductive substance (charge generating substance) have been often used as electrophotographic photosensitive members for electrophotographic apparatuses. The undercoat layer has a charge-blocking function and thus suppresses the charge injection from the support to the photosensitive layer. Consequently, formation of image defects such as black spots is suppressed.
In recent years, charge generating substances having higher sensitivity have been used. However, such an increase in the sensitivity of charge generating substances results in an increase in the amount of charge generated. As a result, charge easily remains in the photosensitive layer, which poses a problem in that ghosts are easily formed. Specifically, a so-called “positive ghost” phenomenon in which an image density increases only in a portion irradiated with light in the previous rotation or a so-called “negative ghost” phenomenon in which an image density decreases only in a portion irradiated with light in the previous rotation easily occurs in an output image.
PTL 1 discloses a technique in which an undercoat layer includes a metal oxide particle and a compound having an anthraquinone structure as a technique of suppressing such a ghosting phenomenon. PTL 2 discloses a technique in which a charge generating layer in a multilayer photosensitive layer includes a phthalocyanine pigment and a compound having an anthraquinone structure.
In recent years, for example, with an increasing number of electrophotographic apparatuses having a color function, higher speed and higher image quality have been required for such electrophotographic apparatuses, and higher performance has been also required for electrophotographic photosensitive members. For example, the degradation of image quality caused by a ghosting phenomenon needs to be suppressed in various environments.